Reliable, flexible, and configurable enough to solve the mail routing needs of any web site, sendmail has withstood the test of time, but has become no less daunting in its complexity. Even the most experienced system administrators have found it challenging to configure and difficult to understand. For help in unraveling its intricacies, sendmail administrators have turned unanimously to one reliable source--the bat book, or sendmail by Bryan Costales and the creator of sendmail, Eric Allman. Now in its third edition, this best-selling reference will help you master the most demanding version of sendmail yet.The new edition of sendmail has been completely revised to cover sendmail 8.12--a version with more features and fundamental changes than any previous version of the Unix-based email routing program. Because the latest version of sendmail differs so significantly from earlier versions, a massive rewrite of this best-selling reference was called for.The book begins by guiding you through the building and installation of sendmail and its companion programs, such as vacation and makemap. These additional programs are pivotal to sendmail's daily operation. Next, you'll cover the day-to-day administration of sendmail. This section includes two entirely new chapters, "Performance Tuning" to help you make mail delivery as efficient as possible, and "Handling Spam" to deal with sendmail's rich anti-spam features. The next section of the book tackles the sendmail configuration file and debugging. And finally, the book wraps up with five appendices that provide more detail about sendmail than you may ever need. Altogether, versions 8.10 through 8.12 include dozens of new features, options, and macros, and this greatly expanded edition thoroughly addresses each, and provides and advance look at sendmail version 8.13 (expected to be released in 2003).With sendmail, Third Edition in hand, you will be able to configure this challenging but necessary utility for whatever needs your system requires. This much anticipated revision is essential reading for sendmail administrators.

Bryan Costales

is CTO with SL3D, Inc. in Boulder, Colorado. He has been active in system administration for over fifteen years and has been writing articles and books about computer software for over twenty years. His most notable books are C from A to Z (Prentice Hall), Unix Communications (Howard Sams), and, of course, sendmail (O'Reilly & Associates).

Our look is the result of reader comments, our own experimentation, and feedback from distribution channels. Distinctive covers complement our distinctive approach to technical topics, breathing personality and life into potentially dry subjects. The animal on the cover of sendmail, Third Edition is a flying fox, a species of fruit bat found chiefly on the islands of the Malay-Indonesia archipelago. Of about 4,000 species of mammals, nearly one-quarter are bats; and of these, 160 are fruit bats. Sixty of the larger fruit bats make up the flying foxes, the largest having a wingspan of five feet. While smaller insect-eating bats navigate by echolocation, fruit bats depend on a keen sense of sight and smell to perceive their environment. They roost in trees by day, sometimes in extremely large numbers called "camps." They hang from branches by one or both feet, wrap themselves in their wings, and sleep the day away. On hot days, these bats keep cool by fanning themselves with their wings.Greatly elongated fingers form the main support for the web of skin that has allowed these mammals, alone, to master true flight. At sunset they awaken from their slumber and begin their nocturnal ramblings. A flying fox must flap its wings until it becomes horizontal to the ground before it can let go and fly away. Once airborne, they use their sensitive sense of smell to detect where flowers are blooming or fruits have ripened. Unlike most animals, fruit bats cannot generate vitamin C (a limitation shared by humans and guinea pigs); thus, it is supplied by fruit in the diet. Flying foxes can range up to 40 miles for food. Once a target is located, they are faced with a difficult landing. Sometimes they will simply crash into foliage and grab at what they can; other times they may attempt to catch a branch with their hindfeet as they fly over it and then swing upside-down; some will even attempt a difficult half-roll under a branch to grip it in the preferred position. Once attached and hanging, they will draw the flower or fruit to their mouths with a single hindfoot, or the clawed thumbs at the top of each wing. These awkward landings often cause fights among flying foxes, especially upon their return to camp at dawn. A single bad landing can cause an entire bat-laden tree to become highly agitated, full of fighting and screaming residents.People have eaten flying foxes for ages. Samoans, who call the flying fox manu lagi (animal of the heavens) use branches bound to the end of long poles to swat the winged delicacy from the sky. Aborigines in Australia build fires beneath flying fox camps-- the smoke stupefies the prey -- and use boomerangs to knock the creatures to the ground. Darren Kelly was the production editor, George Jansen was the copyeditor, and Audrey Doyle was the proofreader for sendmail, Third Edition. Mary Brady, Linley Dolby, Matt Hutchinson, and Claire Cloutier provided quality control. Reg Aubry, Genevieve d'Entremont, and Judy Hoer provided production support. Brenda Miller updated the index from the second edition.Edie Freedman designed the cover of this book. The cover image is a 19th-century engraving from the Dover Pictorial Archive. Emma Colby produced the cover layout with QuarkXPress 4.1 using Adobe's ITC Garamond font.David Futato designed the interior layout. This book was converted to FrameMaker 5.5.6 with a format conversion tool created by Erik Ray, Jason McIntosh, Neil Walls, and Mike Sierra that uses Perl and XML technologies. The text font is Linotype Birka; the heading font is Adobe Myriad Condensed; and the code font is Lucas-Font's TheSans Mono Condensed. The illustrations that appear in the book were produced by Robert Romano and Jessamyn Read using Macromedia FreeHand 9 and Adobe Photoshop 6. This colophon was written by Michael Kalantarian.